For instance, the movable objects include a vehicle, a ship and an aircraft, which are powered by electric power discharged from a battery system mounted on the movable object. In the battery system of this type, it is well known to use a battery pack with a combination of rechargeable cells. Particularly, as a battery system mounted on a movable object requires a measurable amount of electric power, it is known to increase a discharge capacity by connecting a plurality of battery packs in parallel or in series.
For instance, disclosed in Patent Literature 1 is a battery system equipped with a plurality of battery packs and a memory provided integrally in each battery pack for storing information about charge and discharge states of the battery packs such as a charge level and a temperature of the battery pack. Upon charging or discharging the battery packs, a controller refers to the information stored in the memories so as to fully charge the battery packs in an ascending order of a remaining charge level, and fully discharge the battery packs in a descending order of a remaining charge level.